why we celebrate Old New Year

A long time ago there was were two calendars: Julian and Gregorian. In Julian was there were 365 days every a year. In Gregorian, 365 or 366. Every fours year in Gregorian we have the 29th of February.
When While most of countries have been living with using Gregorian, Russia went on live with Julian. When in England it was the 1st of January, in Russia it was the 14th of January.
When we changed our calendar, we invented s new holiday and called it Old New Year.

[I thought that a parenthetical comment would be a cleaner way of expressing the leap year concept. Also, the idea of "living with something" implies a hardship, so I kept that terminology for Russian with Julian, but not for the other countries with Gregorian.]

Wwhy we celebrate the Old New Year

A Llong time ago there werewas two calendars: Julian and Gregorian. In Julian whas 365 days every year. In Gregorian has 365 or 366 days (every four years, February has 29 days instead of 28). Every fours year in Gregorian we have 29th of February.
When most of countries were already using have been living with Gregorian, Russia continued went on liv eing with JYulian. When in England it was the 1st otf January, in Russia it was the 14th of January.
When we changed our calendar to Gregorian, we invented a new holiday and called it Old New Year.